A wiper arm of this kind is known from the German patent specification No. 35 23 546. This known wiper arm has a two-armed lever mounted on the fastening member and pivotable about a shaft mounted perpendicularly to the longitudinal direction of the wiper arm. An adjusting member mounted within the wiper shaft acts upon the first arm of the lever which is closest to the wiper shaft. A pressure spring connects a link and a wiper rod projecting into the link with the second arm of the lever. In order to regulate the contact pressure between a wiper blade attached to the wiper rod and the windshield, the lever can be continuously adjusted between two positions. Because of the possibility of adjusting the contact pressure this known wiper arm is suitable for windshield wiper systems of motor vehicles which can be driven very rapidly. If the vehicle speed is very high the contact pressure must be higher than usual, so that the wiper blade mounted on the wiper rod cannot be lifted off the windshield by the slip stream.
In this known wiper arm, to replace the wiper blade the link can be rotated about an axle into a replacement position, in which the line of application of the pressure spring between the wiper rod and the second lever arm lies beyond the dead center line of the spring relative to an articulated axle between fastening member and link. The lever is fully extended in the replacement position, and the link is offset from its operating position by an angle of about 85.degree.. Such a large angle is unfavourable for various reasons. On the one hand this known wiper arm cannot be used in windshield wiper systems in which the wiper arm is covered by body portions in the area of the fastening member, particularly in the area of the link. On the other hand the link and the parts connected with it (wiper rod and/or wiper blade) can impact the windshield with great force if the link is moved by hand from the tilted position into the parking position and is erroneously released too early. The window shield or the wiper arm can be heavily damaged as a result of such an impact.